Anti-Rotation Device And Method For Alternate Deployable Electric Submersible Pumps

ABSTRACT

An anti-rotation device for and method of preventing rotation of alternate deployable electrical submersible pumps (ESP&#39;s) within a well casing. This anti-rotation device includes a mandrel connected with the ESP (or ESP string) and a torque anchor connected with an inner surface of the well casing. A portion of the mandrel is configured to engage an inner surface of the torque anchor is such a manner as to prevent rotational movement of the mandrel (and ESP) within the well casing. The mandrel may be of variable length and configured to allow variable and selective positioning of the ESP within the well casing. The interaction of the mandrel and the torque break also provides for alignment of the ESP within the well casing. Additionally, it absorbs and dissipates pump induced torque for the ESP.

CROSS-REFERENCE TO RELATED APPLICATION

The present document is based on and claims priority to U.S. Provisional Patent Application Ser. No. 61/748,390, filed Jan. 2, 2013, the entire subject matter of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to electrical submersible pumps (ESP). More specifically, the invention provides systems and methods for preventing rotational movement of alternate deployable ESP or ESP strings in a down well application.

BACKGROUND

In a typical (ESP) application, torque generated by energizing the motor is transmitted to a rigid structure, such as production tubing joints or coiled tubing. This rigid tubing also prevents the ESP from rotating naturally with the rotation of the pump. In the case of an ESP deployed on a cable (flexible) or other member of insufficient torsional strength (referred to herein as “alternate deployable”), such a rigid mechanism to absorb torque and prevent rotation of the ESP string does not exist. This introduces the need for an anti-rotation device to stabilize the ESP and ESP string. Conventional anti-rotation devices must be landed and stay in that position during ESP operation, which is a disadvantage.

By way of example, in some conventional alternate deployable ESP systems, the anti-rotation mechanism used is a seating shoe. This type of device has two halves. One half is connected to the ESP and the other half must be installed as part of the casing string. This type of application has limitations on the location of the ESP in the well bore and can be costly to change, when needed. Additionally, some conventional alternate deployable systems are locked into the casing string via the static seating shoe. Similar features are also used in some completion segments and may be referred to as a “mule shoe.” Due to limitations on setting location within the well bore and difficulties and costs related to workovers when a malfunction of the seating shoe occurs, the conventional technique is not desirable for current alternate deployable systems.

SUMMARY

Aspects of the present invention provide techniques for addressing the aforementioned problems and shortcomings. According to one aspect, an anti-rotation device for operation of an electric submersible pump (ESP) in a well casing includes a self-guiding mandrel connected with the ESP and a torque anchor connected with the well casing, the torque anchor being configured to receive a portion of the self-guiding mandrel.

According to another aspect, an ESP a system includes a keyed mandrel and a slotted housing to fit around the keyed mandrel and connected with an ESP. Additionally, included in the system is a torque anchor connected with a well casing, said torque anchor being configured to slideably receive a portion of the mandrel with a helical alignment feature and form a torque anchor.

According to yet a further aspect, a method of limiting rotation of an ESP in a cased well includes providing a cased well and providing an ESP within the cased well. Additionally, the method includes providing a mandrel connected with the ESP and providing a torque anchor with an inner surface of the cased well. Still further, the method includes introducing a portion of the mandrel into the torque anchor.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and the advantages thereof may be acquired by referring to the following description in consideration of the accompanying drawings, in which like reference numbers indicate like features, and wherein:

FIG. 1 is a plan view of an exemplary ESP string configuration according to an aspect of the invention;

FIG. 2 is a sectional view of an exemplary anti-rotation device according to an aspect of this invention;

FIGS. 3 a and 3 b are an isometric views of a portion of a slotted mandrel having helical features and bullnose according to certain aspects of the invention;

FIGS. 4 a and 4 b are an isometric views of a slotted mandrel having helical feature according to another aspect of the invention;

FIGS. 5 a and 5 b are an isometric views of a keyed mandrel configured according to another aspect of the invention;

FIG. 6 is an isometric view of an exemplary multiple-slotted mandrel according to another aspect of the invention;

FIGS. 7A and 7B are partial isometric exploded views of certain aspects of a key retaining system according to an aspect of the invention;

FIG. 8 is a sectional view of portion of an internal helical feature according to another aspect of the invention; and,

FIG. 9 is a flow chart depicting an exemplary method of using certain aspects of the invention.

DETAILED DESCRIPTION

Features, systems, and methods associated with anti-rotation devices for ESP's are detailed herein. These features, systems, and/or methods represent possible implementations and are included for illustration purposes and should not be construed as limiting. Moreover, it will be understood that different implementations can include all or different subsets of aspects described below. Furthermore, the aspects described below may be included in any order, and numbers and/or letters placed before various aspects are done for ease of reading and in no way imply an order, or level of importance to their associated aspects.

The present invention is directed towards apparatus, systems and methods for alternate deployable ESPs, in which the deployment itself (e.g., by flexible cable) does not provide rigidity and stability to the ESP and ESP string against the torque generated by the ESP motor and other rotational forces at play. The anti-rotation apparatus, systems and methods provide structure to align, prevent rotation, and absorb torque in an ESP deployment.

Referring now to the figures, in which like numerals represent like elements, an embodiment will be described. FIG. 1 illustrates an exemplary alternative deployable ESP system 20. The alternative deployable ESP system 20 is positioned within a well casing 30 at a selective well depth determined by length of cable 24. The alternative deployable ESP system 20 typically includes at least one pump 26 and at least one electric motor 28, that when combined, with or without other structure, form an ESP 22 (or ESP string 22). Additionally, alternative deployable ESP system 20 includes a mandrel 34 connected with the ESP 22 that is configured to engage a torque anchor 36 positioned within the well casing 30. The mandrel 34 and torque anchor 36 function to align the ESP 22 within the well casing 30, absorb ESP torque and prevent ESP rotation within the well casing 30. A more detailed description of the alternative deployable ESP system 20 is described below.

With reference to FIGS. 1 and 2, in an implementation, the mandrel 34 may be of any desired length. In certain instances a relatively short mandrel 34 may be selected. Conversely, other instances a relatively longer mandrel 34 may be desired. It will be appreciated that the overall length of the mandrel 34 (and positioning of the torque anchor 36 discussed below) allow the ESP 22 to be positioned at any depth within the well casing 30. This allows for optimal or ideal ESP 22 positioning independent from well casing 30 depth. As best seen in FIGS. 2 and 3, attached to the lower end of the mandrel may be an optional perforated bullnose 40 that aids in centralizing the mandrel 34 and also allows flow to enter the annulus during ESP operation. However, the use of a bullnose 40 is not required and the end of the mandrel 34 can be left open (as best seen in FIGS. 4 and 5).

The torque anchor 36 is typically configured to engage an inner surface of the well casing 30 and to permit passage of a portion of mandrel 34 there through. The engagement of an outer surface of the torque anchor 36 with an inner surface of the well casing 30 is substantially rigid in nature. Although the torque anchor 36 position within the well casing 30 is completely user selective and may be either removable or fixed, in operation, there should be no relative motion between the elements.

With reference to FIG. 2, in an implementation, a Seal Bore Extension 32 (may also be known as or by Polished Bore Receptacle) may be used as part of a structure that connects the mandrel 34 with the ESP 22. The Seal Bore Extension 32 may be of a variety of structures and form depending upon the nature of the implementation. One example includes the use of housing key 38 and slot 39 combination between the Seal Bore Extension 32 and the mandrel 34. Likewise, any number of seal unit(s) 42 may be employed as may be dictated by design or selected structure. It will be appreciated that housing key 38 and slot 39 (also seen in FIGS. 7A and 7B) function to prevent relative motion between the Seal Bore Extension 32 and the mandrel 34. The housing key(s) 38 and slots 39 are sized to withstand the torque produced when the motor is energized and prevent rotation of the ESP and any subsequent damage to other equipment in the string. The number of keys can also vary compared to the number of slots in the mandrel. The key(s) can be located above or below the SBE or PBR which may be installed above or below the torque anchor 36 and/or anywhere between other completion equipment. The housing key 38 and slot 39 features may also be reversed. That is, the key(s) 38 can be a part of the mandrel 34 and run along its entire length or portion thereof. The helical alignment feature and slot can then be on the inside diameter of a sub or housing. These features may also assume various shapes and the housing keys 38 and slots 39 may be captured in place in various ways.

As best seen in FIGS. 3A and 3B-8, 4A and 4B, and 6, in an implementation, the mandrel 34 includes at least one helical alignment feature 46 configured to engage a respective alignment slot 48 in the torque anchor 36. In another configuration, the helical alignment feature 46 is positioned on an inner surface of the torque anchor 36 and the respective alignment slot 48 or tab 38 on the mandrel (not shown). In operation, the keyed or slotted mandrel 34 is slideably engaged with the keyed or slotted torque anchor 36. The resulting combination provides a structure that aligns the ESP 22 within the well casing 30, and also prevents any rotation of the ESP 22 relative to the well casing 30.

In an implementation, the mandrel 34 (or torque anchor 36) may possess any number of helical alignment feature(s) 46. Similarly, the corresponding torque anchor 36 (or mandrel 34) map possess any number of alignment slot 48 or tab 38. The number of respective elements is a matter of design choice. For example, one may choose to use more helical alignment features 46 where a relatively larger torque is anticipated. Perhaps fewer if less torque is anticipated, or vice versa. Regardless, the specific configuration shall be sufficient to function as intended and withstand any designed torsional loading.

The helical alignment feature(s) 46 may also include vertex point(s) 47 one their leading edges. By vertex point(s) 47 what is intended is that the helical alignment feature(s) 46 may be beveled or otherwise tapered inwardly to help facilitate alignment with the torque anchor 36.

In an implementation, the mandrel 34 may include self-aligning helical features that lead into one or more slots. The self-guiding helical alignment feature(s) 46 may be similar to those used in some subsea safety valves and control systems to align multiple electrical and hydraulic stabs between pieces of equipment. These features are herein incorporated by reference.

The mandrel 34 is hollow and defines a passageway 44, which allows flow to the ESP. The passageway 44 defines an inside diameter flow area for a formation to pass through.

In an implementation, mandrel 34 can reside above or below the seal unit(s) 42 that are installed inside the Seal Bore Extension 32 in an ESP 22. The seal unit(s) 42 and mandrel 34 with alignment helix and slot(s) are attached to the lower end of the ESP and are installed into the well along with the ESP 22, e.g., via alternate deployment. The seal units 42 and PBR are part of the completion and may or may not be included as part of the example anti-rotation device.

In addition, mandrel 34 can then be installed as part of a ESP 22, sticking upward, as in a “stinger.” (not shown) Then, a Seal Bore Extension 32 attached to the bottom end of the ESP 22 can be lowered over this “stinger” to perform to anti-rotation functions described here within.

The implementation may be used in offshore fields where the footprint of the rig and weight are restricted, and alternate means of deployment are required. However, use of the example anti-rotation system is not limited to offshore deployment; the system can be used onshore or in many other fields.

With particular reference to FIGS. 5A and 5B, an additional aspect is depicted. Specifically, the alignment feature 46 is shown as a substantially straight key like structure. A respective alignment slot 48 is positioned in an inner surface of the torque anchor 36. This is intended to show that the overall geometry of the alignment feature 46 and respective slot 48 or key 38 (FIG. 6) is variable. The respective elements may be of any geometric shape. Likewise, either element (tab or slot, etc.) may be on either the mandrel 34 or the torque anchor 36. Their specific geometric selection, location, number, etc. is a design choice and may depend or vary based upon application. Sufficient strength and functionality a part of the design considerations. The specific number, location and geometry, etc. is not intended to limit the scope of this application in any way.

Looking at FIGS. 7A and 7B, a further aspect is disclosed. Specifically, a clearer look at an aspect of one possible structure for rotationally locking mandrel 34 (not shown in this Figure). Specifically, this non limiting, exemplary keyway sub 35 is configured to receive an end of the mandrel 34, opposite the end engaging the torque anchor 36. Key(s) 38 engage the mandrel 34 and prevent rotation relative to the keyway sub 35. A cover 33 may sit over the housing key(s) 38 helping to hold the key(s) 38 in place. The cover 33 may be held in place by any known structure, such as, without limitation, snap rings, a threaded cover 33, welded cover, etc. Likewise, the key(s) 38 may be held in place by any known structure. Such structure is not intended to limit the scope of this disclosure.

Likewise, the keyway sub 35 may be connected with the SBE (or PBR) or any other structure associated with the ESP or ESP string 22. This is merely being shown as one non limiting way of rotationally securing the mandrel 34. This non limiting exemplary depiction, used in combination with torque anchor 36 engagement otherwise prevents rotation of the ESP. Those skilled in the art will realize that specific structure or configurations of ESP may be variable. As such, the specific structure for securing the mandrel 34 opposite the end engaging the torque anchor 36 may well vary depending upon design and is not intended to limit this disclosure.

FIG. 8 depicts the helical alignment feature 46 being of slightly different location than the previous figures. In this particular configuration, the helical alignment feature 46 is shown on an inner surface (as discussed above). The figure also shows some alternative method of connection various pieces together. It is not intended to be limiting, rather merely just exemplary of non limiting features that may be used. For example, without limitation, welded joint(s) 43, screw set(s) 41 (or other fastening structure) may also be included, or omitted. Likewise, curve 39 is just one non limiting example of an alignment profile that may be used. As discussed above, the profile may be curved, or straight, or combinations thereof without departing from the spirit and scope of this disclosure.

FIG. 9 depicts a non limiting, exemplary method 60 of using the alternative deployable ESP system. The method includes providing a cased well at a block 62. Also, an alternative deployable ESP system is provided within the well casing at a block 64. The method also includes providing a slotted or keyed mandrel connected with the alternative deployable ESP at a block 66. Further, a slotted or keyed torque anchor is provided within and connected with the well casing as best depicted at a block 68. In an implementation, a keyed or slotted mandrel is introduced into a keyed or slotted torque anchor at a block 70. The introduction of the keyed or slotted mandrel into a keyed or slotted torque anchor is configured to withstand at least any torsional loading provided by operation of the alternative deployable ESP.

Unlike the seating shoe previously used with conventional alternate deployed systems and conventional anti-rotation devices, the example anti-rotation device does not limit the location of the ESP inside the well bore and does not require the string to be “sat down” onto or “landed” rigidly into any receptacle. The ESP 22 and example mandrel 34 can move up and down with the key(s) engaged for a given length, depending on the length of the mandrel 34, itself. This feature allows for the anti-rotation devise to remain dynamic and allows for variability in the setting depth of the ESP. Likewise, the feature allows for expansion/contraction of the ESP string due to temperature or forces produced by pumping or environment.

An anti-rotation device for operation of an electric submersible pump (ESP) in a well casing includes a self-guiding mandrel connected with the ESP and a torque anchor connected with the well casing, the torque anchor being configured to receive a portion of the self-guiding mandrel.

In certain configurations, the device also includes a self-aligning helical keyway or slot.

In certain configurations, the device also includes the self-aligning helical keyway or slot is on an outside surface of the mandrel.

In certain configurations, the self-aligning helical keyway or slot is on an inside surface of a keyed housing.

In certain configurations, the anti-rotation device stabilizes the ESP against a torque, while allowing vertical play of the ESP.

In certain configurations, the anti-rotation device stabilizes the ESP against a torque, while allowing an expansion and contraction of the ESP.

In certain configurations, the device also includes a bullnose, wherein the bullnose allows fluid flow through the bullnose.

In certain configurations, the mandrel has multiple slots.

An ESP a system includes a keyed mandrel and a slotted housing to fit around the keyed mandrel and connected with an ESP. Additionally included in the system is a torque anchor connected with a well casing, said torque anchor being configured to slideably receive a portion of the keyed mandrel.

In certain configurations, the system also includes helical self-aligning slots.

A method of limiting rotation of an ESP in a cased well includes providing a cased well and providing an ESP within the cased well. Additionally, the method includes providing a mandrel connected with the ESP and providing a torque anchor within an connected with an inner surface of the cased well. Still further, the method includes introducing a portion of the mandrel into the torque anchor.

In certain configurations, the method also includes providing a bullnose connected with an end of the mandrel, wherein the bullnose allows fluid flow through the bullnose.

In certain configurations, the method also includes providing a mandrel connected with the ESP further includes providing at least one key engageable with at least one slot on the torque anchor.

In certain configurations, the method also includes providing an ESP, includes providing at least on pump and at least one electrical motor.

In certain configurations of the method, the torque anchor is provided downwell from the ESP.

In certain configurations of the method, the torque anchor is provided upwell from the ESP.

Although only a few embodiments of the present invention have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this invention. Accordingly, such modifications are intended to be included within the scope of this invention as defined in the claims. 

What is claimed is:
 1. An anti-rotation device for operation of an electric submersible pump (ESP) in a well casing, comprising: a self-guiding mandrel connected with the ESP, and; a torque anchor connected with the well casing, the torque anchor being configured to receive a portion of the self-guiding mandrel.
 2. The apparatus of claim 1, further comprising a self-aligning helical keyway or slot.
 3. The apparatus of claim 2, wherein the self-aligning helical keyway or slot is on an outside surface of the mandrel.
 4. The apparatus of claim 2, wherein the self-aligning helical keyway or slot is on an inside surface of a keyed housing.
 5. The apparatus of claim 1, wherein the anti-rotation device stabilizes the ESP against a torque, while allowing vertical play of the ESP.
 6. The apparatus of claim 1, wherein the anti-rotation device stabilizes the ESP against a torque, while allowing an expansion and contraction of the ESP.
 7. The slotted mandrel with helical features of claim 1, further comprising a bullnose, wherein the bullnose allows fluid flow through the bullnose.
 8. The slotted mandrel with helical features of claim 7, wherein the mandrel has multiple slots.
 9. An ESP a system, comprising: a keyed mandrel; a slotted housing to fit around the keyed mandrel and connected with an ESP; and, a torque anchor connected with a well casing, said torque anchor being configured to slideably receive a portion of the keyed mandrel.
 10. The system of claim 9, wherein the housing includes helical self-aligning slots.
 11. The system of claim 9, where the torque anchor includes helical self-aligning slots.
 12. A method of limiting rotation of an ESP in a cased well, comprising: providing a cased well; providing an ESP within the cased well; providing a mandrel connected with the ESP; providing a torque anchor connected with an inner surface of the cased well; and, introducing a portion of the mandrel into the torque anchor.
 13. The method of claim 12, further comprising providing a bullnose connected with an end of the mandrel, wherein the bullnose allows fluid flow through the bullnose.
 14. The method of claim 12, wherein the step of providing a mandrel connected with the ESP further includes providing at least one key engageable with at least one slot on the torque anchor.
 15. The method of claim 12, wherein the step of providing an ESP, includes providing at least on pump and at least one electrical motor.
 16. The method of claim 12, wherein the torque anchor is provided downwell from the ESP.
 17. The method of claim 12, wherein the torque anchor is provided upwell from the ESP. 